Testing device



Patented oer. 19,1926.

HALSEY ntrnnnnaickgbnMountain; LAKES, anias-nnllissieitfilt e nt r ELECTRIC conning,mqonponnmnn;:oF NEWEORIQ1\{;-Y,;;;;A

new YO K,

a ew-1stweave;-e m; w 1

i This I invention relates "1:61 devices an d m e pec fically-Iq i z i pa tle l well: adapted fen use i'fol; test' and thelike. p l vhen i telephone,transmitters;have been submittedt o long use, it has been found'lthat arcing betweenl the carbon granules. execs sive heatiand other causes gradually. affect thee characteristics of the 5 transmitter; and V or produce :Ln oise which renders the? telephone; conversation unintelligible. QThQe laboratory transmitter; testing machines now in usel liave f to ofcostly and their; operationfto o complex for use recovery: and repair shops and the, object oflthis invention is i to providecainetho d ofgiand fapparatus, for, testing transmitters which willbe "simple t to operate, accurate, cheap to manufacture,

and wherein;- the; burning condition ,of telephone transmitters may be determined in a simple manner. 7 i

-From a large amount of-data taken on transmitters obtained from various repair shops, it'was determined that there *was. sufiiclent correlation between m'ax mum I burning and minimum current of transmitiers when tested by burnlngtest methods to accept or reject transmitters for burning on the basis of the1r minimum'current readdngs only. It was determined that trans- I niitters through which the current readings were above'a certain amount were acceptable-and'those below could be re ected as Z inefficient.

I A feature of the. invention is the provision of means whereby the amount of burning or'related defects in the transmitterbutton 1 mg operation.

is visually indicated;

Another feature is the provision of means for producing a uniform amount. of:noise in the transmitter. I

V p Another feature is' the provision of means 3 I whereby the transmitter and receiver are insulated from outs de nolse dur ng the test- Another, feature is the provision of means whereby the electrical circuit may becontrolled in a simple and positive manner. i Other features and advantages will ap- 1 pear from the following description and bythe' claims appended thereto, reference being had to the accompanying drawings in which Fig; 1 is a diagrammatical-view of the test clins rineinnvion flei l a ein or ryi s elerllen iitraeeim t phone receiver [connected to normally well-knowntyp of- .t Lon i sideof 1o" i i e ryv stamen bf a tt r? has it filiertrm llcemiecte to the lead '14:, thuscom lirougli the telephone re s ening was; t shqw'nl dapted y clamping "the transmitter22 to be tested 75 one terminal connected to one terminal of 'minal of transmitter 22 may be connected to for completing a testing circuit which in- .thereby completing a calibrating circuitin may; with i h shown in. 1* ig I iconsji'sts of an ordinary tel open contact sp ngs' lland 1 27 o'fan inter 'rupter.Dfzwhichf inayb'efinithefform'of an I calling di'alj'oranyot r I a a a oi'; uniform y nak nd 1 bre king it lef' ir ili w h hi i I ociated- 1jCoh actflspri g'rl l i e e ea injuxta'position with the receiver 10 and'to. insulate them from outside noise during the testing operation. The transmitter 22 has avariable resistance 16 which includes wiper 8U 23 connected to lead 26jwhich has its other endconnectedto battery 13 ,The other ter- H one side of anammeter 17 through a switch ing member 18, which rests on" a contact 20 8;,

eludes the lead 24. Switching member 18 is also adapted tov be moved on contact ,19; of an impedance device 21 to 'forma calibrating circuit the functionof wh'i clrwill be hereinafter described. Y Q t The operation of the'testing'i device is as follows:v'lhetransmittertobe tested is placed "in. the casing 15 the cover closed to insulate-f the [transmitter 22Qfrom outsidenoise and to hold the transmitteranouthpiecetightly against the earpiece of the receiver 10 as 5 shovvnin the drawing. The s\vitch ,18-'isg moved. in contacting'relation with contact Q i 19.for connecting the" impedance 21 and loo .jf'

i erated. to cause a series of makes and breaks I it 'in this circuit.- The diaphragm of the re Thecurrent flowing through the transmit t'er when it is substituted for r the fixed resistance should'not be less than the predetermined value mentioned above which service it tested in a circuit in which the resistance in series with the transmitter is approximately equal to or greater than that ofthe transmitter itself. It is obvious that 1 the dial of the ammeter 17 may bevgraduated in burning units instead of amperes or in each value in correlation to the other; also that the corresponding voltage across the transmitter might: be measured. instead i ceiver in juxtaposition, meansfor insulating said transmitter' and said receiver from outside noise, a circuit tor said receiver including an interrupter, a circuit including a fixed and a'variable resistance and a meter, corresponds to the maximum burning per'' v 'inissible for a satisfactory transmitter. This condition is graphically indicated in the curve shown in'Fig. 2 where the current a circuit including said transmitter and'said variable resistance, and a manual switch for controlling said latter circuits.

:2. In a testing set, a sound proof casing,

a transmitter and a receiver in juxtaposition therein, an interrupter circuit including said receiver and said interrupter, a fixed resistance substantially equal to the maximum allowable transmitter resistance, a variable resistance,. a meter, a calibrated circuit in cluding said resistances and meter, and a manual switch for substituting saidtrans mitter for said fixed resistance.

In witness whereof, I hereunto subscribe j my name this 15th day of October A. D., 1924. r I

HALSEY A. FREDERICK. 

